According to page 15 in this self-test guide from the UK, the test results are reported either online via their https://www.gov.uk/report-covid19-result website or by a telephone call. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/957271/COVID-19-self-test-instructions.pdf Your step-by-step guide for COVID-19 self-testing